Hello Heba,

You could consider using mass balance approach for something that is easy to measure (e.g., water evaporation from emitting soil) and then correlate it with flux of target gases of interest.  See this publication for ideas.:

Parker, D.B., N.A. Cole, K.D. Casey, G. Galvin, R. Ormerod, C.S. Paris, E.A. Caraway, M.B. Rhoades. 2009. Wind tunnels vs. flux chambers: Area source emission measurements and the necessity for VOC and odour correction factors. Proceedings 19th International Clean Air and Environment Conference, Perth, Australia, September 6-9, 2009.

Jacek

Thanks So much Jacek,

This correct, but I also want to know if there a direct method such as titration or something simple to measure CO2, CH4 and N2O from incubated soil samples?

http://www.sciencedirect.com/science/article/pii/S0165993613002574

Thanks so much Ali,

it really good paper

You can use soda lime method also to measure CO2 emission from soil. 

see this article for the soda lime method that Zsolt suggested:

Keith, H. and Wong, S.C., 2006. Measurement of soil CO 2 efflux using soda lime absorption: both quantitative and reliable. Soil Biology and Biochemistry, 38(5), pp.1121-1131.

Thank you Debjani, this article is what I suggested. :)

Hi Zsolt-I figured that...

Tanks so much to both of you Zsolt and Dabjani, I also hope to find other method for CH4 or N2O.

My regards,

For simple methods, please go to Munir et al. 2015, Munir et al. 2014 in Biogeosciences. I hope these to be helpful

Soda lime method creates a lot of biases and is not really recommended for any estimates. I suppose, you can use cheap optical sensors (100-500$) for CO2 and methane but it will work only for a strong sources. For N2O it seems impossible up to the moment.

Thanks so much Alexander it is realy a good idea.

dear heba, i agree with Alexander Faritovich Sabrekov

I think, this option is the most cost-effective and reliable for CO2 (sensor is described in paper): http://www.biogeosciences.net/12/3849/2015/bg-12-3849-2015.html

For methane and N2O there are no cheap options for small fluxes.

Agree with Alexander Faritovich Sabrekov

I think the labour intensive nature of flux surveys is often overstated. I can routinely make 100 - 200 flux measurements per day on my own. However, this does depend on they type of measurement you are doing - spatial or temporal, and the suitability and responsiveness of the equipment you are using. There is a lot of work required to produce an accurate flux meter. Have you looked at the time it takes vs the $ to buy a West Systems Diffuse Flux Meter or a Li-COR equivalent? 

good luck